This invention relates to internal combustion engines fed with a fuel gas obtained in a reformed gas generator in general and more particularly to an improved method of operation for such internal combustion engines.
Methods of operating internal combustion engines with a fuel gas obtained from a gas generator rather than with a liquid fuel are known. Such methods are used because liquid fuel leads to incomplete combustion in the internal combustion engine. This is the result of insufficient carburation and poor mixing with combustion air leading to the presence of harmful substances in the exhaust gas. Antiknock agents which are mixed to the fuel result in additional pollutants which are injurious to the health. The level of harmful emissions to the air from an internal combustion engine can be substantially reduced if the engine is operated with a fuel gas obtained, for example, from the reaction of a liquid hydrocarbon fuel and an oxygen containing gas in a reformed gas generator.
The type of gas generator which is being referred and the manner of operating such is described, for example in U.S. application Ser. No. 633,609 filed Nov. 20, 1975 which is a continuation in part of U.S. application Ser. No. 439,870 filed Feb. 6, 1974 now abandoned. In the method disclosed therein atomized or evaporated liquid fuel containing hydrocarbons is fed, after having air and/or exhaust gas fed back from the internal combustion engine mixed with it, to the reaction chamber of a reformed generator where it is catalytically reacted to form a fuel gas containing carbon monoxide, carbon dioxide, methane and/or hydrogen. This fuel gas burns more completely in the internal combustion engine and results in an extremely low level of harmful exhaust gases. Furthermore, it has a high octane number making the addition of antiknock agents unnecessary.
For use in an internal combustion engine, fuel gas containing carbon monoxide and methane is desireable because of the high calorific value of this mixture. A fuel gas can be burned in the combustion chamber of the engine more completely and with better control if it contains hydrogen. Furthermore, in order to achieve sufficient filling of the combustion chamber of the internal combustion engine with fuel gas, it is desireable to feed a fuel gas which is as cool as possible. It is very difficult to fulfill all these requirements which the fuel gas should simultaneously meet. Furthermore, if the reaction of hydrocarbons with a gas containing oxygen takes place at low temperatures, up to the thermal equilibrium, soot occurs. Formation of soot, however, can lead to the destruction of the catalyst or even damage or destruction of the internal combustion engine and must be prevented through the use of suitable catalysts. In some circumstances, this requires a toleration of levels of carbon monoxide, methane and hydrogen in the fuel gas produced which does not meet what are considered as the most favorable combustion properties.
In view of these various problems, the need for an improved method of operating an internal combustion fed with a reformed fuel gas becomes evident.